More than 200 known diseases are transmitted through food. The causes of food-borne illness include viruses, bacteria, parasites, toxins, metals, and prions. See “Computerized Teaching Materials for the Infectious Diseases Course at KCOM” by Dr. Neal Chamberlain. The symptoms of food-borne illness range from mild gastroenteritis to life-threatening neurological (for example, botulism; Clostridium botulinum), hepatic (for example, Hepatitis A), and renal syndromes (for example, E. coli O157:H7). Food-borne diseases cause about 76 million illnesses, 325,000 hospitalizations, and 5,000 deaths in the United States each year. Known pathogens account for an estimated 14 million illnesses, 60,000 hospitalizations, and 1,800 deaths with Salmonella, Listeria, and Toxoplasma, being responsible for 1,500 deaths each year. Unknown agents account for the remaining 62 million illnesses, 265,000 hospitalizations, and 3,200 deaths.
According to data reported by Mead et al. 1999, the following are the most common microbial causes of food-borne illnesses.
TABLE 1Most Common Microbial Causes of Food-borne IllnessPercentage ofEstimated TotalFood-BorneDisease or AgentCasesTransmissionNoroviruses (Norwalk-like viruses)23,000,00040Campylobacter species2,500,00080Giardia lamblia2,000,00010Salmonella1,400,00095Shigella450,00020Cryptosporidium parvum300,00010Clostridium species250,000100Toxoplasma gondii225,00050Staphylococcus aureus185,000100Shiga toxin-producing110,00085Escherichia coli (STEC)Yersinia enterocolitica100,00090Bacillus cereus27,000100Cyclospora cayetanensis16,00090Listeria monocytogenes2,50099
Surveillance of food-borne illnesses is complicated by the fact that a proportion of such diseases is caused by pathogens or agents that have not yet been identified and thus cannot be diagnosed. Further, many of the pathogens that are of greatest concern today (e.g., Campylobacter jejuni, Escherichia coli O157:H7, Listeria monocytogenes, Cyclospora cayetanensis) were not recognized as causes of food-borne illness just 20 years ago. Therefore, there remains the need for developing better methods for detecting microbial food-borne pathogens.
Due to interference of various inhibitors, tests for pathogens were limited to sample sizes of about 25 grams at their maximum. As a result, testing of large amounts of specimens, such as raw or uncooked foodstuffs, required numerous tests in order to verify the specimen did not contain pathogens. Such testing was tedious and expensive because a significant amount of tests were needed to verify that no pathogens existed in the specimen. Accordingly, a need also exists for testing sample sizes greater than what is conventionally available while obviating the problems associated with conventional methods.
The instant invention aims to address this need by providing methods and compositions for rapid and accurate detection of microbial and viral pathogens in food samples.